Magnetoelectric phase diagrams of orthorhombic RMnO3 (R=Gd, Tb, and Dy)
Magnetoelectric phase diagrams of orthorhombic RMnO3 (R=Gd, Tb, and Dy)
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DOI：
10.1103/physrevb.71.224425
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发表时间：
2005-06-01
影响因子：
3.7
通讯作者：
Ramirez, AP
中科院分区：
文献类型：
--
作者：
Kimura, T;Lawes, G;Ramirez, AP
研究了具有正交畸变钙钛矿结构的稀土锰矿RMnO3 （R=Gd， Tb和Dy）的磁电相图。在这些体系中，随着r位离子、温度和磁场的变化，出现了各种各样的磁相和电相。相对于结晶轴，磁电相图随磁场方向敏感地变化。虽然离子半径R（R(R)）最大的GdMnO3在零磁场（H=0）下基态不是铁电相，但在b轴上施加H(>类似于1 T)，会出现沿a轴电极化(P)的铁电相。TbMnO3和DyMnO3都显示出沿c轴P的铁电序，即使在低于锁定转变温度的H=0时，磁调制和晶格调制的非零波矢量几乎是恒定的。当沿a或b轴施加H时，这些系统也表现出铁电极化的翻转（P平行于c到P平行于a）。相反，在c轴上施加类似于10t的H，完全抑制了TbMnO3中的铁电性。考虑到钙钛矿型稀土锰的磁性和晶格畸变，讨论了观察到的磁电相演化的可能起源。
Magnetoelectric phase diagrams have been investigated for rare-earth manganites with orthorhombically distorted perovskite structure, RMnO3 (R=Gd, Tb, and Dy). A variety of magnetic and electric phases emerge with varying R-site ion, temperature, and magnetic field in these systems. The magnetoelectric phase diagram varies sensitively with the direction of a magnetic field relative to the crystallographic axes. Although the ground state of GdMnO3 with the largest ionic radius of R(r(R)) is not ferroelectric in zero magnetic fields (H=0), a ferroelectric phase with electric polarization (P) along the a axis appears by applying H(>similar to 1 T) along the b axis. Both TbMnO3 and DyMnO3 show a ferroelectric order with P along the c axis even at H=0 below a lock-in transition temperature where nonzero wave vectors for magnetic and lattice modulations become nearly constant. These systems also exhibit a flop of the ferroelectric polarization (P parallel to c to P parallel to a) when H is applied along the a or b axis. By contrast, the application of H above similar to 10 T along the c axis completely suppresses the ferroelectricity in TbMnO3. Possible origins of the observed evolution of magnetoelectric phases are discussed in consideration of magnetism and lattice distortion in the perovskite rare-earth manganites.